Mechanical properties of B–C–N films synthesized by an electron beam excited plasma-CVD method

We have synthesized B–C–N films by an electron beam excited plasma-CVD method and characterized structures and properties of the obtained films. In this paper, tribological properties of the films under dry-lubrication were investigated with a ball-on-disc type friction tester. The hardness of the films increases monotonically with increasing boron content and both the friction coefficient and the wear rate increase with increasing the hardness. From these results the low friction coefficient can be attributed to the formation of a sp2-bonded B–C–N structure. And it is suggested that the cause of the wear for the B–C–N films may be a microscopic peeling, because the film should become more brittle and the internal stress of the film should become larger for the harder film.